Introduced a getter for change flags, making a related helper function private.

Do not print a '*' at the end of hydrogen instruction mnemonics with side
effects, this is subsumed by the 'changes' info.
Review URL: http://codereview.chromium.org/7827009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9092 ce2b1a6d-e550-0410-aec6-3dcde31c8c00